This invention relates to a method and apparatus for viewing three dimensional objects to promote a greater understanding of their structure.
It is desirable to be able to view a three dimensional (3-D) object, especially a complex object such as a molecule, in such a way as to understand its structure. A number of methods for viewing 3-D objects have been devised to help with this understanding.
U.S. Pat. No. 4,941,041, of Kenyon and entitled "Pulfrich Illusion Turntable" teaches a method that utilizes the Pulfrich illusion for converting two dimensional (2-D) images into pseudo 3-D images by placing video cameras and subjects on a large turntable. In the Pulfrich illusion, the eye of an observer which is closer to a viewing screen (e.g. a television monitor) sees a moving object on the screen a fraction of a second before the other eye sees the moving object. This situation presents an illusion of duality to the brain, which converts the flat pictures that the eyes are actually seeing to an illusion of 3-D pictures.
U.S. Pat. No. 4,414,565, of Shanks and entitled "Method and Apparatus for Producing Three Dimensional Displays", teaches a method for generating an illusion of a 3-D image from a 2-D image by projecting the 2-D image on a saddle-shaped surface. This saddle-shaped surface may be a real surface such as a light scattering glass or a surface in space formed by an optical component such as an aspheric lens or lenticular array. The saddle-shaped surface helps a viewer appreciate 3-D clues present in most 2-D images.
U.S. Pat. No. 4,558,359, of Kuperman et al. and entitled "Anaglyphic Stereoscopic Image Apparatus and Method", describes an image processing apparatus which aids in the analysis of images by introducing additional physically displaced image elements in complimentary colors. The additional image elements are generated by the digital processing of original image elements. The added elements and original image are viewed stereoscopically on an electronic reconstructed image display.
U.S. Pat. No. 4,462,044, of Thomason et al. and entitled "Timing System for a Three Dimension Vibrating Mirror Display", concerns changing the focal properties of a mirror so as to create a 3-D image from several 2-D images presented in rapid succession. The system includes an anisochronous clock which varies its clocking rate in proportion to the momentary velocity of movement through the display volume so that the displayed image planes are equally spaced throughout the depth of the display volume.
It is often desirable to be able to present 3-D images on the 2-D display of a computer system. For example, in computer-aided design (CAD) and 3-D modeling systems, machines, machine parts, and other 3-D objects can be displayed in an isometric or perspective view on the screen of the computer system. Many of such systems permit the 3-D objects to be rotated or viewed from different angles to permit a visual inspection of the object. In such a rotation, the object is typically turned by 180 degrees around a selected axis at some point in the cycle. However, for an observer to relate what is observed before and after the rotation takes quite a bit of mental gymnastics, and many intermediate depth perception clues are not provided.
Many algorithms are known to be useful in generating these 3-D images on a computer screen. These algorithms can be implemented in software, hardware, or a combination of the two. Examples of such algorithms include hidden line and surface generating algorithms, and shading algorithms such as ray tracing algorithms and radiative algorithms. Such algorithms and methods for implementing such algorithms are well known to those skilled in the art.
There are also stereoscopic methods that involving goggles, polarized light, for generating 3-D images by presenting each eye with a slightly different image. Such systems promote eyestrain and headaches if used over long periods of time, and are sometimes hard to focus. Holograms also produce 3-D images of objects, but these images tend to be of poor resolution and do not necessarily permit a tidier understanding of the objects.